1. Field of the Invention
This invention relates primarily to power driving circuits, and more particularly, to a power driving circuit which efficiently utilizes the power from inductively driven loads and internal transformers by returning this inductively derived power to the power source and in addition, monitors the voltage applied to the power sources during driving to provide an extremely regulated voltage amplitude.
2. Description of the Prior Art
In certain applications, such as in sheet feeding, solenoid type devices are required to drive a member in an intermittent motion. One such device is described in U.S. Pat. No. 3,747,921, to L. F. Knappe, entitled, "Document Feed Device". In this patent, as well as a copending application Ser. No. 537,732 entitled "Document Transport and Separating Device", by O. D. Johnson, filed on the same day as the subject application and assigned to a common assignee, there is provided one such device. In this patent and application a number of intermittent motion transport devices are utilized to propel paper along a paper path. The operation of these devices is such that a driving tip is driven by a solenoid such that the end of the tip moves in an elliptical path to propel the paper down the selected path. At the bottom of the ellipse, which is formed by the driving of the solenoid armature and the return of it to its unenergized position, the tip contacts the paper and drives it in the direction in which the ellipse is rotating. The voltage applied to the solenoids which drive the tips must be controlled and must remain constant regardless of the number of solenoids being driven at one time. In addition, efficient use of the power supply is also desired.
Previous drive circuits have either utilized heat sinks to dissipate the power induced by the inductive kick when the solenoids are deenergized such that the power is not only wasted, but additional costs are incurred due to the utilization of heat sinks. In addition, where multiple devices were connected to a power driver it was extremely difficult to control the voltage level to make the devices operate properly when the devices were being switched in and out of operation, and thus, a limited number of devices could be driven by a single source. The ideal solution to this control voltage problem was quite expensive in that to assure proper operation at the control voltage, single regulated power drivers were required for each of the solenoid type of devices. Obviously this last solution was quite expensive and did not result in a viable system even though reliable operation could be achieved.